Methods and apparatus for reducing gas turbine engine emissions

Abstract

A method enables a gas turbine engine to be assembled. The method comprises coupling a fuel nozzle within the engine to inject fuel into the engine, wherein the fuel nozzle includes three independent injection circuits arranged such that the second injection circuit is between the first and third injection circuits, coupling a liquid fuel source to a first injection circuit defined within the nozzle and including an annular discharge opening, and coupling a water source to one of the second injection circuit and the third injection circuits such that the water source is coupled in flow communication to an annular discharge opening.

1. A method for assembling a gas turbine engine, said method comprising:
 coupling a fuel nozzle within the engine to inject fuel into the engine, wherein the fuel nozzle includes three independent injection circuits arranged such that the second injection circuit is between the first and third injection circuits; 
 coupling a liquid fuel source to a first injection circuit defined within the nozzle and including a first annular discharge opening; and 
 coupling a water source to one of the second injection circuit and the third injection circuits such that the water is coupled in flow communication to a second annular discharge opening, such that the water is discharged from the second annular discharge opening at a wider spray angle than that of the liquid fuel discharged from the first annular discharge opening. 
 
   
   
     2. A method in accordance with  claim 1  wherein coupling a liquid fuel source to a first injection circuit further comprises coupling a liquid fuel source to a primary injection circuit and to a secondary injection circuit. 
   
   
     3. A method in accordance with  claim 1  further comprising coupling one of the second injection circuit and the third injection circuit to a gaseous fuel source. 
   
   
     4. A method in accordance with  claim 1  further comprising coupling one of the second injection circuit and the third injection circuit in flow communication to a gaseous fuel source such that the gaseous fuel is coupled in flow communication to a plurality of circumferentially-spaced discharge openings. 
   
   
     5. A method in accordance with  claim 4  wherein coupling one of the second injection circuit and the third injection circuit in flow communication to a gaseous fuel source further comprises orienting the nozzle such that the first and second injection circuits discharge flow therefrom in a direction that is substantially parallel to an axis of symmetry extending through the nozzle, and such that the third injection circuit discharges flow therefrom in an oblique direction with respect to the axis of symmetry. 
   
   
     6. A fuel nozzle for a gas turbine engine, said fuel nozzle comprising:
 a first injection circuit comprising an annular discharge opening, said first injection circuit for injecting liquid fuel downstream from said nozzle into the gas turbine engine; 
 a second injection circuit aligned substantially concentrically with respect to said first injection circuit; 
 a third injection circuit aligned substantially concentrically with respect to said first injection circuit, said first injection circuit is between said second and third injection circuits, one of said second and third injection circuits for injecting water downstream from said nozzle into the gas turbine engine, one of said second injection circuit and said third injection circuit comprising an annular discharge opening; and 
 a centerline axis of symmetry, said third injection circuit comprises a plurality of circumferentially-spaced discharge openings configured to discharge fluids obliquely outward from said nozzle with respect to said centerline axis of symmetry. 
 
   
   
     7. A fuel nozzle in accordance with  claim 6  wherein said first injection circuit comprises a primary fuel circuit and a secondary fuel circuit, said primary fuel circuit radially inward from said secondary fuel circuit. 
   
   
     8. A fuel nozzle in accordance with  claim 7  wherein only said primary fuel circuit is configured to inject fuel into the gas turbine engine during engine start-up and idle operating conditions. 
   
   
     9. A fuel nozzle in accordance with  claim 6  further comprising a centerline axis of symmetry, said first injection circuit is a radial distance from said centerline axis of symmetry. 
   
   
     10. A fuel nozzle in accordance with  claim 6  wherein one of said second injection circuit and said third injection circuit comprises a plurality of circumferentially-spaced discharge openings. 
   
   
     11. A fuel nozzle in accordance with  claim 6  wherein one of said second injection circuit and said third injection circuit is configured to only inject gaseous fuel downstream from said nozzle into the gas turbine engine. 
   
   
     12. A gas turbine engine comprising a combustor comprising a combustion chamber and at least one fuel nozzle, said at least one fuel nozzle comprising a first injection circuit, a second injection circuit, and a third injection circuit, and a nozzle discharge tip, said first injection circuit comprising a first annular discharge opening, said first injection circuit for injecting only liquid fuel into said combustion chamber, said second injection circuit is aligned substantially concentrically with respect to said first and third injection circuits, such that said second injection circuit extends between said first and third injection circuits, one of said second and third injection circuits comprises a second annular discharge opening, one of said second and third injection circuits is for only injecting water into said combustion chamber, wherein the water exits said second annular discharge opening at said nozzle discharge tip, and the liquid fuel exits said first annular discharge opening upstream from said nozzle discharge tip. 
   
   
     13. A gas turbine engine in accordance with  claim 12  wherein said first injection circuit comprises a primary fuel circuit and a secondary fuel circuit, said primary fuel circuit radially inward from said secondary fuel circuit. 
   
   
     14. A gas turbine engine in accordance with  claim 13  wherein said primary fuel circuit is configured to inject liquid fuel into said combustion chamber only during engine-start up and idle operating conditions. 
   
   
     15. A gas turbine engine in accordance with  claim 13  wherein one of said second injection circuit and said third injection circuit is configured to only inject gaseous fuel into said combustion chamber. 
   
   
     16. A gas turbine engine in accordance with  claim 13  wherein said nozzle comprises an axis of symmetry extending therethrough, said first injection circuit is oriented to discharge liquid fuel from said nozzle in a direction that is substantially parallel to said axis of symmetry. 
   
   
     17. A gas turbine engine in accordance with  claim 13  wherein said nozzle comprises an axis of symmetry extending therethrough, said second injection circuit is oriented to discharge water from said nozzle in a direction that is substantially parallel to said axis of symmetry, said third injection circuit is oriented to discharge gaseous fuel from said nozzle in an oblique direction with respect to said axis of symmetry. 
   
   
     18. A gas turbine engine in accordance with  claim 13  wherein said nozzle comprises an axis of symmetry extending therethrough, said third injection circuit comprises a plurality of circumferentially-spaced openings configured to discharge gaseous fuel from said nozzle in an oblique direction with respect to said axis of symmetry. 
   
   
     19. A gas turbine engine in accordance with  claim 13  wherein said nozzle comprises an axis of symmetry extending therethrough, said first injection circuit is a radial distance from said centerline axis of symmetry.